In modern high speed disc drives, the recording head slider is usually maintained at a very small distance above the recording media. Typically, this distance is 25 nm. The disc is lubricated to improve its durability. Modern discs usually use a long chain polymer lubricant.
When disc heads fly over the disc for long periods of time, disc lube can accumulate on the slider. Once the disc drive is shut down and the disc stops spinning, the slider with the accumulated lube is parked on the disc. The accumulated lube transfers from the slider to the disc and can be held at the slider/disc interface by meniscus forces. This large amount of disc lubricant at the slider/disc interface may be responsible for the high stiction forces observed between slider and disc.
Lube can also accumulate on both the trailing edge of the slider and in the cavities downstream of the side rails of typical center transducer sliders. When the disc stops, the lube in the cavity will often wick along the rail edges and cause high stiction. Some recording heads use surface energy modifying agents to prevent lubricant from accumulating preferentially on the slider.
On sliders, carbon pads are typically fabricated on the air bearing rails to enhance tribology. These carbon pads are deposited using photolithographic processes.
FIG. 1 shows disc lube 103 accumulating at the trailing edge of a rail 101 of a typical modern slider 100. The air flow 104 in this diagram is generally in an downward direction as the air travels through the air bearing channel 102. The lube tends to preferentially accumulate at the trailing edge of the side rails 101.
FIG. 2 shows a similar situation. In FIG. 2, lube 201 has accumulated in the cavity just down stream of the trailing edge of the air bearing rail 202 of a slider 200, which is just outside the air bearing channel 202. Lube 204 has also accumulated in the area of the interface between the slider substrate and the basecoat/overcoat alumina. This lube accumulation along the alumina can wick along the alumina/substrate edge until it reaches the center pad and then onto the disc. Once the lube reaches the disc/pad interface, it can cause high stiction forces. It is therefore desirable to find a mechanism that controls lube flow across the slider.
The present invention provides a method and system for reducing accumulated disc lube. More particularly, the present invention relates to a method and apparatus for channeling lube off recording disc head sliders using pads.
Accordingly, the present invention provides a slider for supporting a transducer next to a lubricated recording medium. The slider includes a pad positioned to control a flow of lubricant. The slider can also include a raised rail. The pad can be positioned on the slider between the raised rail and a trailing edge of the slider. The pad can extend to the trailing edge of the slider. The pad can include at least two separated edges, which form a central channel. The pad can be made of carbon. The pads can be approximately 0.03-1.00 micron tall in a cavity that is approximately 2 micron deep. The pad can be angled in relation to an air flow across the slider to control lube.
In another embodiment, the present invention provides a method for fabricating a slider for supporting a transducer next to a lubricated recording medium. The method includes depositing a pad on the slider positioned to control a flow of lubricant. The method can include forming a raised rail. The pad can be deposited between the raised rail and a trailing edge of the slider. The pad can extend to the trailing edge of the slider. The pad can comprise at least two separated edges forming a central channel. The pad can be deposited using photolithographically patterned material. The pad can be made of carbon. The pad can be deposited at an angle in relation to an air flow across the slider to control lube.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Implementations can provide advantages such as preferentially controlling accumulation of lubricant at the trailing edge of slider rails. This invention can also be used to prevent wicking of lubricant along the interface between the slider substrate and basecoat or overcoat alumina. The pads can aid in controlling the flow of lubricant off the air bearing surface. The pads can also be used to reduce the flow of the lubricant along the substrate/alumina interface, which can help reduce the resulting stiction.